1. Field of the Invention
The present invention relates to a semiconductor manufacturing process, and more particularly to a method of forming a shadow layer on a wafer bevel region.
2. Description of Related Art
In general, the fabrication of an integrated circuit involves forming a multi-layered stacked structure through various techniques. Each layer in the multi-layered stacked structure performs a particular function such as serving as a conductive layer, a dielectric layer, an insulating layer or an adhesion layer for increasing an adhesive strength between two adjacent layers. Frequently, each of the layers is fabricated with use of different materials to enhance the performance of devices. Besides, after the multi-layered stacked structure is formed, an etching process is implemented in most cases so as to pattern the multi-layered stacked structure for forming the required devices.
However, during the implementation of the etching process (especially a plasma etching process), the layers disposed on a wafer bevel region are easily damaged. Thereby, defects may often occur, and the devices are then adversely affected. Thus, in the manufacturing process of a multi-layered stacked structure at present, a shadow ring is usually formed on the wafer bevel region before the etching process is performed so as to protect the layers on the wafer bevel region.
FIGS. 1A through 1C are cross-sectional views illustrating a conventional process of manufacturing a shadow ring on a wafer bevel region.
First, with reference to FIG. 1A, a shadow material layer 106 is formed around a substrate 100. The substrate 100 has a wafer bevel region 102 and a central region 104. A multi-layered stacked structure (not shown) is already formed on the substrate 100. The shadow material layer 106 is usually made of oxide.
Then, with reference to FIG. 1B, a patterned photoresist layer 108 is formed over the substrate 100 to partially cover the shadow material layer 106. The patterned photoresist layer 108 covers the shadow material layer 106 in the wafer bevel region 102.
Next, with reference to FIG. 1C, a wet etching process is performed to remove a portion of the shadow material layer 106 which is free of the patterned photoresist layer 108. Thereafter, the patterned photoresist layer 108 is removed, so as to form a shadow layer 110. The shadow layer 110 surrounding the substrate 100 is usually called the “shadow ring”.
However, at least three steps are required during the process of forming the shadow layer 110, and one of the steps must be a photolithography process. Thus, manufacturing costs are increased.